Four police officers beat and mocked a man suspected of being a terrorist who helped al-Qa'ida, a court heard today.

The Metropolitan Police officers were arresting Babar Ahmad in his London home when they administered "a very violent assault: in effect, they gave him a beating or they beat him up", it was claimed.

The policemen were part of the Territorial Support Group, assisting the Anti-Terrorist Branch in taking Ahmad into custody during a dawn raid on his home in Fountain Road, Tooting, south London, on December 2, 2003.

The trial of the officers started today - more than seven years after the alleged assault.

Ahmad was never charged in relation to his arrest but is in custody awaiting extradition to America for alleged terrorism offences.

The British courts granted the extradition but Ahmad appealed and the case has not been resolved, the jury heard.

The four accused of assaulting Ahmad are police constables Mark Jones, Roderick James-Bowen and Nigel Cowley, and Detective Constable John Donohue.

They deny the offence.

The officers, dressed in helmets and protective clothing, smashed their way into Ahmad's home just after 5am and ran upstairs, where he had been in bed with his wife.

Before launching the raid, the officers were briefed that Ahmad had received terrorist training and fought overseas in support of jihad - holy war.

The operation came 11 months after Detective Constable Stephen Oake was murdered in Crumpsall, Manchester, by a terror suspect named Kamel Bourgass.

Police feared their target would resist.

"The reality was quite different," said the barrister, saying he remained entirely submissive.

"Dressed only in his pyjamas and barefooted, Mr Ahmad raised his arms above his head to indicate that he was not going to fight or to present any sort of danger or threat to the police."

But the Territorial Support Group (TSG) were not "going to take any chances", said Mr Laidlaw.

One defendant, James-Bowen, was first into Ahmad's bedroom and "threw himself at Mr Ahmad, knocking the victim back against the bedroom window, which smashed".

Mr Laidlaw told the seven men and five women of the jury that the officers then exceeded what was acceptable.

He said: "The officers began to shout and swear, calling Babar Ahmad a 'f****** b******' and a 'f****** c***' and he was punched and beaten to the floor.

"On the floor the assault continued as his wife called out for the police to stop.

"She was then removed from the bed and taken out of that room.

"Handcuffs were then applied, with his hands having been secured behind his back so by this stage, even if minded to resist, Mr Ahmad's physical ability to do so would have been severely compromised.

"But still, and despite the restraint now in place, the assault continued."

The victim was taken downstairs to his prayer room and put in the position Muslims adopt to pray.

Mr Laidlaw said the officers then asked "Where is your god now?".

Ahmad was put in a police van and driven to Charing Cross police station.

"During that journey the assaults continued," said the prosecutor.

"There was more punching, further pulling up and pressure being applied by the manhandling of the handcuffs and Mr Ahmad was held in headlocks. The taunting and verbal abuse also continued."

When the victim arrived "battered and bruised" at the station, the defendants pretended to the custody sergeant that he was very violent in his resistance.

"It was a lie that all four defendants persist with to this day," said the QC.

Mr Ahmad's arrest was part of an anti-terror operation named Operation Quarrier in which three other properties were also raided.

The victim, whose house had been bugged by the Security Service, MI5, was suspected of being the leader of a group who provided al Qaida and other fundamentalist networks with computer, financial and logistical expertise.

Mr Laidlaw urged the jury not to be distracted by this.

The court heard that the defendants were briefed before the raid about the importance of showing "due consideration" "to the islamic beliefs of the occupants of the homes to be searched".

There was also a separate cultural briefing from a senior muslim officer.

From his bedroom, Mr Ahmad, 37, was taken to his prayer room with Cowley, 34, Jones, 43, and Donohue, 37. James-Bowen, 40, was not involved in the assaults that allegedly ensued.

Inside the prayer room the trio smashed a glass candlestick, which was a wedding present, and kept on their steel toe-capped boots.

Mr Laidlaw said: "As they took Mr Ahmad into the room one of their number asked, adopting a sarcastic tone, 'Are we allowed to wear shoes in here?' and there was laughter as they, still wearing boots, took Mr Ahmad into the room."

The mocking continued, said the QC, with Mr Ahmad's handcuffs being pulled and the officers laughing as he was asked: "Where is your god now?"

"His pyjama bottoms were pulled down and again his genitals were touched with a gloved hand.

"It was obviously another attempt to humiliate".

Mr Ahmad was transferred to a police van and made to lie in the central aisle between the seats.

Mr Laidlaw said: "In that position he was punched to the back and left kidney and there was more swearing.

"As the van drove away, one of the two officers sitting down by the victim's legs crossed Mr Ahmad's ankles, so one was on top of the other, and then applied pressure whilst at the same time, twisted his handcuffs.

"The officer sitting nearest to Mr Ahmad's head asked where he was born and when he replied 'London', that officer punched him to the back of the head and demanded: 'Which hospital you f****** b******?'

"That same officer then lifted Mr Ahmad's body and held him in a headlock with both arms.

"After releasing him the same officer said: 'You f****** c***, you'll remember this day for the rest of your life, do you understand me? You f****** b******.'

"There was further twisting of the handcuffs and another headlock applied before the van reached Charing Cross police station."